Field of the Invention
The present invention relates to wireless power transmission.
Description of the Related Art
A wireless power transmission system including a power transmission apparatus which wirelessly transmits power and a power reception apparatus which receives the power supplied from the power transmission apparatus has conventionally been known. In such a wireless power transmission system, a power transmission apparatus detects a power reception apparatus existing within a power-transmittable range by detection power transmission of weak power, and performs authentication processing on the detected power reception apparatus based on authentication power transmission. If the authentication succeeds, the power transmission apparatus then starts charging power transmission of higher power to the power reception apparatus (Japanese Patent Application Laid-Open No. 2013-212004). A wireless power transmission system in which a power transmission apparatus can simultaneously perform power transmission to a plurality of power reception apparatuses is also known.
If a power transmission apparatus of a power transmission system which performs authentication processing as discussed in Japanese Patent Application Laid-Open No. 2013-212004 simultaneously performs power transmission to a plurality of power reception apparatuses, a problem can arise in that the power transmission apparatus performs authentication processing even on a power reception apparatus that does not receive power.
For example, when the power transmission apparatus performs charging power transmission to a first power reception apparatus, the power transmission range is wider than that of the detection power transmission and the authentication power transmission since the power of the charging power transmission is higher than that of the detection power transmission and the authentication power transmission. If a second power reception apparatus is placed relatively close to the power transmission apparatus while the power transmission apparatus is performing the charging power transmission to the first power reception apparatus, the second power reception apparatus can detect the charging power transmission being performed to the first power reception apparatus. The second power reception apparatus responds to the charging power transmission being performed to the first power reception apparatus in the same manner as to the detection power transmission and the authentication power transmission, and starts the authentication processing on the power transmission apparatus. In such a case, the power transmission apparatus and the second power reception apparatus may perform the authentication processing therebetween even if the second power reception apparatus does not need to be charged.